Redux Toolkit:错误:操作必须是纯对象。使用自定义中间件进行异步操作

import { createSlice, createAsyncThunk } from '@reduxjs/toolkit';

// 创建异步操作的Thunk
const fetchUser = createAsyncThunk('user/fetchUser', async (userId, thunkAPI) => {
  // 执行异步操作，比如发送网络请求
  const response = await fetch(`/api/users/${userId}`);
  const data = await response.json();

  return data;
});

// 创建slice
const userSlice = createSlice({
  name: 'user',
  initialState: { data: null, loading: false, error: null },
  reducers: {},
  extraReducers: (builder) => {
    builder
      .addCase(fetchUser.pending, (state) => {
        state.loading = true;
      })
      .addCase(fetchUser.fulfilled, (state, action) => {
        state.loading = false;
        state.data = action.payload;
      })
      .addCase(fetchUser.rejected, (state, action) => {
        state.loading = false;
        state.error = action.error.message;
      });
  },
});

// 导出reducer和异步操作的Thunk
export const { reducer } = userSlice;
export { fetchUser };